eng Science and Education Publishing American Journal of Medical Case Reports 2374-216X 2022-01-23 10 2 35 38 10.12691/ajmcr-10-2-4 AJMCR20221024 article Takeshi Koga takekoga@saitama-med.ac.jp 1 Moe Yoshimura 1 Sakiko Kubo 1 Miki Nagai 1 Katsuhiko Tabata 1 Hiromi Teranishi 1 Misato Fujino 1 Hiroshi Kawana 1 Ikuma Musha 1 Yuko Akioka 1 Department of Pediatrics, Saitama Medical University Hospital, Saitama, Japan Our case report presents a young patient vaccinated for coronavirus disease 2019 (COVID-19) who developed multisystem inflammatory syndrome in children (MIS-C), which was later confirmed to be multisystem inflammatory syndrome after vaccination (MIS-V). 15-year-old boy previously infected by COVID-19 who received the first dose of COVID-19 vaccine 50 days later and developed fever, lethargy, headache, diarrhea, nausea, lip swelling, neck pain, and dysphagia. Contrast-enhanced computed tomography revealed a low absorption area with no contrast effect was observed in the posterior pharyngeal gap suggesting retropharyngeal phlegmon. He was diagnosed to be MIS-V level 2 based on the Brighton Collaboration Case Definition and improved by Intravenous immunoglobulin (IVIG). The frequency of neck symptoms in MIS-V is higher than in other febrile diseases, and many cases of retropharyngeal phlegmon are observed. In addition, pediatric COVID-19 is mostly asymptomatic or mild; therefore, it is predicted that children who are unaware of their history of COVID-19 before vaccination are not rare. Therefore, after vaccination, extra care should be required to development of MIS-V in children. http://pubs.sciepub.com/ajmcr/10/2/4/ajmcr-10-2-4.pdf COVID-19 vaccine MIS-C neck pain dysphagia adverse event following immunization child